\!h Change using GRANT, without granting any extra privilages:
GRANT USAGE ON *.* TO 'selina'@'localhost' IDENTIFIED BY 'new_pass'; -- overwritten old password
\!h Another way, using SET PASSWORD:
SET PASSWORD FOR 'selina'@'localhost' = PASSWORD('new_pass');
\!h Shorter if you're logged in as that user:
SET PASSWORD = PASSWORD('new_pass');
\!h Remove a password with SET PASSWORD:
SET PASSWORD FOR 'selina'@'localhost' = '';